Supercharger for internal combustion engines



April 27', 1937. s. R. PUFFER SUPERCHARGER FOR INTERNAPQGMBU-STI ON ENGINES Filed Aug. 51, 1953 Inven'GoP Samuel R. Puffefi,

H s Attovneg Patented Apt. 27, 1937 SUPERCHARGER FOR INTERNAL COM- BUSTION ENGINES Samuel R. Puiien Saugus, Mass.,-assignor to General Electric Company, a corporation of New York Application August 31, 1933, Serial No. 687,588

. Claims. The present invention relates to superchargers for internal combustion engines, more particularly, aeroplane engines.

The object of the invention is to provide an improved construction and arrangement of supercharger, and for a consideration of what I believe to be novel and my invention, attention is directed to the following application and the claims appended thereto.

In the present instance, the invention is shown applied to an internal combustion engine of the radial type. It is to beunderstood, however, that it is not limited thereto necessarily. It is also shown as being applied to an engine using a carburetor. It is to be understood, however, that it can be used equally well with engines using other means of supplying fuel to the cylinders.

In the drawing, Fig, 1 is an end view looking toward the right hand side of Fig. 3, of a supercharger embodying my invention, the gearing and the wall enclosing the gearing in Fig. 3 being omitted; Fig. 2 is an end view of a part of the structure shown in Fig. 1 viewed from the opposite side and partly broken away; Fig. 3 is a sectional view taken on line 3-3, Fig. 2, and Fig. 4 is a diagrammatic perspective view of an operating means for the control valves.

Referring to the drawing, Ill indicates an end crank case wall of a radial type engine. It is providedwith an openingin which is located a bearing II for the engine crank shaft I2. Fastened directly to end wall II) by a ring of bolts I3 is a supercharger embodying my invention. It comprises an outer casing I4 provided with a central partition wall or diaphragm I5 which divides the casing into two parts or stages, a lower pressure part or stage adjacent to the crank case wall III and a higher pressure part or stage on the side of the partition remote from the crank case wall III. Outer casing I4 is formed in two parts, the line of division being indicated at I6, to permit casting of the casing and its assembly, and it is provided'with an annular web II on which partition wall I5 is supported.

In the lower pressure part or stage are walls l8 and I 9 which define an annular inlet chamber 20 and an annular discharge chamber 2 I Also, wall I9 defines with diaphragm I5 an impeller chamber 22 and an annular discharge passage 23 which connects impeller chamber 22 to discharge chamber 2i. Formed integral with diaphragm I5 are a series of spaced curved vanes 24 which are located in passage 23 and serve to define air flow passages shaped to convert velocity into pressure.

Connected to inlet chamber 20 are two inlet pipes 25 which communicate with the atmosphere and are provided with valves 26 mounted on a spindle 21 to which is connected an actuating arm 28. Valves 26 are provided with openings 23 so'that when in closed positions, some air can 5 still fiow past them. In the present instance,

'butterfiy valves are illustrated as this is the type of valve I prefer to use. However, any suitable type of valve may be utilized. As will be clear,

these valves control the supply of air to inlet in chamber 20.

Mounted in suitable bearings 30 and 3| in the end walls of casing I4 is a quill shaft 32 on which is fixed an impeller 33 located in impeller chamber 22. The eye or admission side of impeller 15 33 facestoward wall I0 and communicates with inlet chamber 20. The blades of impeller 33 are indicated at 34.

Connected to discharge chamber 2I are two discharge openings 35 to which are connected dis- 20 charge pipes 36 which lead to' the casing 31 of an air cooler or radiator. Pipes 36 are provided with heat radiating fins 38 for dissipating heat of the air passing through the pipes.

It will be noted that discharge openings 35 are located at opposite sides of discharge chamber 2I and that the discharge chamber 2| is in two sections, each in the form of a scroll as indicated particularly in Fig. 2 wherein 2| indicates one scroll communicating at its larger end with the left-hand discharge opening 35 and 2I indicates the other scroll communicating at its larger end with the right-hand discharge opening 35. Each scroll extends about degrees. This construction gives a symmetrical arrangement for the discharge passages and serves to distribute the air evenly between the two discharge openings 35.

" diaphragm I5 are a series of spaced curved vanes 41 which are located in passage 46 and serve to define air flow passages shaped to convert '50 velocity into pressure.

Connected to inlet chamber 43 is an inlet pipe 48 which at its outer end is connected to the discharge pipe 49 of a fuel carburetor 50. In discharge pipe 49 is a throttle valve 5| mounted on 5 Gil a spindle 52 to which is fixed an actuating arm 53.

Fixed on quill shaft 32 is an impeller 54 located in impeller chamber 45. The eye or admission side of impeller 54 faces in a direction opposite to that of impeller 33 and communicates with inlet chamber 43. The vanes of impeller 54 are indicated at 55. Connected to discharge chamber 44 are a series of circumferentially spaced discharge pipes- 56 which lead to the cylinders (not shown) of the internal combustion engine of which the supercharger forms a part. Pipes 56 are equally spaced around discharge chamber 44 and extend first outwardly and then rearwardly to the engine cylinders.

On the outer end of quill shaft 32 is a pinion 51 which meshes with a gear wheel 59 rotatably mounted on a fixed shaft 59. Shaft 59 is supported at one end in a socket 66 in the end wall of casing I4 and at the other end in an opening 6| in a wall 62 attached to casing l4 and forming therewith a gear casing. The portion of thecasing end wall in which socket 66 is located is supported by webs 6|] as shown in Fig. l. On

- shaft 59 is a pinion 63 which meshes with a gear wheel 64 fixed on the outer end of a shaft 65. The outer end of shaft 65 is mounted in a bearing 66 in gear casing wall 62 and its inner end is connected to crank shaft |2. Shaft 65 passes through quill shaft 32 in spaced relation to the walls thereof. Gear wheel 58 and pinion 63 both turn on shaft 59 and they are connected to each other through a suitable slip clutch 61 arranged to slip in case of overload 'on the gears. Any

. suitable form of slip clutch may be used.

Gear casing wall 62 and inlet pipe 48 are formed integral with each other and they are provided with a flange 68 for use in bolting the structure to casing l4.

The inlet of carburetor 58 is connected to the casing 31 of the air cooler so as to receive air from the pipes 36 after it has been cooled in the air cooler. The-air cooler may be of any suitable construction. In the present instance, it is shown as comprising round tubes 69 provided with flared-out hexagonal shaped ends 18 which are joined together to form solid end walls. Only a few of the tube ends are shown on the drawing but it will be understood that the entire area within the boundary of lines A is made upof tube ends. The upper side of the bank of tubes is closed by a cover plate TI and the surrounding sides and bottom of the tubes are enclosed by walls 12 and 13. As will be clear from Fig. 1, the arrangement issuch that air from pipes 36 is spread out on all sides of tubes 69 and passes up over them to the carburetor. Air from the atmosphere flows through tubes'69 forming a cooling medium. The air cooler may be so located on an aeroplane that it faces in the direction of travel so there will be a good flow of air through the tubes. It may be suitably supported on a part of the aeroplane. In cover plate 1| are one or more inwardly opening air supply valves 14 which open to supply air from atmosphere directly to the inlet of the carburetor in case the pressure in the air cooler decreases below that of the surrounding atmosphere. Any suitable type of valve may be used. In the present instance, the valve is shown as comprising a valve member 15 held against its seat by a spring 16, the lower end of the spring being supported on a cross strap 11 which forms also a guide for the valve stem.

Connected to actuating arm 28 (Fig. 4) is a charger.

spring 18 which serves normally to hold valves 26 in closed positions. Valves 26 are opened against the action of springs I8 by a rod 19 connected at one end to arm 28 and at the other end to an arm 86 on a shaft 8|. v between rod 19 and arm 86 comprises a slot 82 in the rod in which is located a pin 83 on arm 86, thus providing a lost motion connection. On shaft 8| is an arm 84 connected by a link 85 to a hand control lever 86 pivoted on a shaft 81 and movable between stops 88 and 89. Also, on shaft 8| is an arm 98 connected by a link 9| to actuating arm 53 for the throttle valve. When throttle valve 5| is fully open, it strikes a stop 92 and the connection between link 9| and arm 53 is of a character such that after valve 5| is fully open, continued movement of control lever 86 can take place. To this end, link 9| is provided with a relatively long slot 93 at its end in which is located a pin 94 in the end of arm 53, and between the pin and the end of the slot is a spring 95. With this arrangement, after valve 5| strikes stop 92, further movement of link 9| can take place through the compression of spring 95. In Fig. 4, control lever 86 is shown in off position, throttle valve 5| which controls the flow of fuel to the engine and valves 26 which control the flow of air to the lower pressure stage of the super-' charger being closed. It is held normally in this position by a suitable spring 96. As control lever 86 is moved forward, it functions first to open throttle valve 5|, no movement of valves 26 occurring due to the lost motion connection between rod 19 and arm 86. After throttle valve 5| reaches a predetermined open position, which may be fully open position or some intermediate position, pin 83 engages the end of slot 82 so that valves 26 begin to open- When valve 5| is fully open, it strikes stop 92 after which further movement of lever 86 serves to open valves 26. It will be understood that control lever 86 is provided with suitable means (not shown) whereby it may be located in any adjusted position between the two stops 86 and 89.

The construction provides a two stage super- When valves 26 are open, air flows through inlet conduits 25 to the'eye of the first stage impeller 33 and is discharged by it to the two scrolls of discharge chamber 2|. The first stage or lower pressure stage of the supercharger compresses the air to a predetermined pressure. From discharge chamber 2|, the air flows through conduits 36 to the air cooler or radiator 31 and passes over the tubes of the radiator to carburetor 50, or, if no carburetor is used, directly to the inlet of the second stage. In passing through carburetor 56, the air is charged with fuel and passes through inlet conduit 48 to inlet chamber 43 of the higher pressure stage of the supercharger. From inlet chamber 43, the air passes to impeller 54 and is discharged by it to chamber 44. In

passing through impeller 54 and the difiuser surrounding it, the fuel is vaporized and mixed thoroughly with the air, and the mixture is discharged through chamber at a predetermined pressure. From chamber 44, the carbureted air or mixture flows through discharge pipes 56 to the cylinders of the engine.

When operating at light load, or in the case of an airplane, when operating near the ground, little if any supercharging is desired. At such times, throttle valve 5| is only partly open and valves 26 are closed. The closing of valves 26 results, in substance, in cutting out the first stage of the supercharger. When valves 26 are closed, only stable operation of the first stage of the compressor and cool the same. Under these circum-- stances, the pressure in radiator 31 will be ordinarily less than atmospheric pressure so that valves 15 open admitting air directly from the atmosphere to the carburetor. By this arrangement, therefore, the amount of supercharging is controlled automatically by the operating lever 8'6 which, as stated above, operates first to open throttle valve a predetermined amount after which it starts to open valves 25 to put the first stage of the supercharger into use. When valves 26 are closed, only a relatively small amount of air flows through the casing of the first stage of the compressor. This serves to decrease the density of the air in which impeller 33 runs thereby decreasing the power required for turning impeller33 when it is idle.

An important feature of my invention is the arrangement of the two stages of the supercharger so that their inlets face in opposite directions, the inlet of the lower pressure stage facing toward the engine and the inlet of the higher pr ssure stage facing away from the engine. This ermits of the carburetor and cooler being located in front of and below the supercharger and connected directly to the front portion of it. an ad-' vantageous arrangement in'that it positions these parts where they are out of the way of the engine proper and so located that connections to them are made easily and are readily accessible. It is to be understood, however, that in certain respects my invention is not'limited to this arrangement as in the case'of an engine-having no carburetor, or for some other reason, it may be desirab e. to have the arrangement of the superchar er reversed so that the inlet of the high pressure stage is facing toward the engine.

The back to back arrangement of the impellers is advantageous also in that it enables the supercharger to be made of relatively small axial length,

since there are no air passages between the im- 'pellers but only a single wall. Also, in the case of a radial engine,.the arrangement enables the supercharger to be brought within the confines of the engine.

It will be noted meteor flow to the first stage length of the supercharger.-

The carburetor connection is a part of the gear casing and is separate from the supercharger proper- Thus the supercharger is a unit which bolts directly to the engine and the gearing is a 2,078,807 suflicient' air flows through openings 29 to give unit which boltsto the supercharger. By this arrangement, a different supercharger may be used without change in the gearing, or a different gearing 'may be substituted without change in the supercharger. And in either case, the carburetor and cooler are readily connected and disconnected. This is a most advantageous arrangement from a practical standpoint.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. A centrifugal compressor comprising a casing, a wall dividing the easing into two stages, an impeller in each stage having its back adjacent to said dividing wall and its inlet facing outwardly, walls forming two discharge scrolls for the low pressure stage, and a discharge opening a for each discharge scroll.

2. In combination, 'a supercharger member having an inlet and anoutlet, a valve in the inlet, a carburetor having its inlet connected to said supercharger member outlet, a throttle valve for the carburetor, a valve means for supplying air directly to the carburetor, and control means for operating the inlet valve and the throttle valve arranged so-that the inlet valve is opened after the throttle valve is at least partially open. 3. In combination, a supercharger member having an inlet and a plurality of outlets, an air cooler to which the outlets are connected on opposite sides,- a carburetor having its inlet connected to the central portion of the cooler, means for supplyingair directly to 'the air cooler, an inlet valve in the supercharger member inlet, a throttle valve for the carburetor, and means for opening the throttle valve at least partially in advance of said inlet valve.

4. A centrifugal type supercharger comprising a plurality of stages placed bacls to back, the casing of the supercharger being provided onone side with an inlet through which air fiows to 'the supercharger and on the other side with an inlet for connection to a carburetor, a gear casing attached to the. other 'side of the superan inlet with ,a valve for'cont'rolling the flow of air therethrough, a carburetor for receiving compressed air from the supercharger, a throttle valve in the carburetor, and a-control mechanism for-actuating the throttle valve and the inlet valve, said mechanism including a lever connected to the throttle valve and another lever having a lost motion connection between the first named lever-and the inlet valve.

SAMUEL R. PUFFER.

5. The combination of a supercharger having 

